Main trade-off
Thule Force 3 L Sport
The 175 cm ski limit restricts long equipment.
Head-to-head
Thule Force 3 L Sport vs Yakima SkyBox NX 18: Sport preserves neighboring rack space, SkyBox takes longer skis and more bags
The short answer
Choose the Force 3 L Sport when keeping room beside the box matters more than maximum luggage volume. Choose the SkyBox NX 18 for longer skis or larger family bag loads that will use its wider shell. Include every bike carrier and crossbar in the roof-load calculation before deciding that both accessories can travel together.
Before you choose
The reasoning and the trade-offs
The narrow box can make a mixed-load plan easier
A 50-inch usable bar span minus the box width leaves 25.3 inches for the Sport and 14 inches for the NX 18. The Sport therefore creates 11.3 inches more nominal side space before accounting for clamps and rack feet.
What this is based on
50 - 24.7 = 25.3. 50 - 36 = 14. This does not guarantee a bicycle carrier can mount or clear the lid.
Main trade-off
Yakima SkyBox NX XL
The 36-inch width makes side-by-side rack planning harder.
Thule Force 3 L Sport
- Choose it for
- Your skis fit within 175 cm and you need a narrow shell.
- You want a 34 lb box for a weight-sensitive rack setup.
- Main trade-off
- The 175 cm ski limit restricts long equipment.
Yakima SkyBox NX XL
- Choose it for
- You need skis up to 195 cm.
- Your family can use 18 cu ft and the full-width roof layout.
- Main trade-off
- The 36-inch width makes side-by-side rack planning harder.
About this comparison
Compare Force 3 L Sport and SkyBox NX 18 when roof space must serve bikes, longer skis or family luggage without exceeding vehicle load limits.
Choose the Force 3 L Sport when keeping room beside the box matters more than maximum luggage volume. Choose the SkyBox NX 18 for longer skis or larger family bag loads that will use its wider shell. Include every bike carrier and crossbar in the roof-load calculation before deciding that both accessories can travel together.
Winner by situation
Start with what you need it to do
A bike beside a box of short gear
The Sport leaves more nominal width and payload for the second accessory.
- Thule Force 3 L Sport
- Better fit
- Yakima SkyBox NX XL
- Caution
190 cm skis
The NX 18 supports skis up to 195 cm.
- Thule Force 3 L Sport
- Not suitable
- Yakima SkyBox NX XL
- Better fit
Bulky light luggage for a family
The NX 18 provides 18 rather than 11 cu ft.
- Thule Force 3 L Sport
- Caution
- Yakima SkyBox NX XL
- Better fit
A roof load already near its limit
Weigh the rack, box and every other accessory before adding cargo.
- Thule Force 3 L Sport
- Caution
- Yakima SkyBox NX XL
- Caution
What matters in practice
The differences that matter
The narrow box can make a mixed-load plan easier
A 50-inch usable bar span minus the box width leaves 25.3 inches for the Sport and 14 inches for the NX 18. The Sport therefore creates 11.3 inches more nominal side space before accounting for clamps and rack feet.
How we reached this conclusion
50 - 24.7 = 25.3. 50 - 36 = 14. This does not guarantee a bicycle carrier can mount or clear the lid.
Add the bike before filling the box
Assume a 165 lb total roof allowance, 20 lb rack and 35 lb bicycle plus carrier. The Sport leaves 76 lb for box cargo and the NX 18 leaves 57 lb. A larger box may offer empty space that the remaining payload cannot safely use.
How we reached this conclusion
165 - 20 - 35 - 34 = 76. Replacing 34 with 53 gives 57. Use the lowest actual system limit and weighed accessories.
A 190 cm ski reverses the narrow-box preference
If the trip includes 190 cm skis, the NX 18 meets its 195 cm limit while the Sport’s 175 cm limit does not. Removing the bike or choosing another transport layout may be necessary rather than forcing long skis into the narrow box.
How we reached this conclusion
190 is 15 cm beyond the Sport limit and 5 cm below Yakima’s limit. Binding and bag clearance still need checking.
Choice A
Thule, 645650
Force 3 L Sport
A narrow box with the Force 3 mounting and locking hardware, built for smaller loads beside other roof gear.
- Best matched use
- Your skis fit within 175 cm and you need a narrow shell.
Checked facts
- Volume and ski length: 11 cu ft, skis up to 175 cm
- Exterior width: 24.7 in
- Empty weight: 34 lb
- Exterior length: 75.2 in
Choice B
Yakima, SkyBox NX 18 XL
Yakima SkyBox NX XL
The box holds 18 cubic feet. It accepts gear up to 195 centimeters long.
- Best matched use
- You need skis up to 195 cm.
Checked facts
- Volume and ski length: 18 cu ft, skis up to 195 cm
- Exterior width: 36 in
- Empty weight: 53 lb on current product page
- Exterior length: 84 in
Meaningful differences
What changes the fit
| What changes | Thule Force 3 L Sport | Yakima SkyBox NX XL | Why it matters |
|---|---|---|---|
| Volume and ski length | 11 cu ft, skis up to 175 cm | 18 cu ft, skis up to 195 cm | The Yakima takes longer gear and more bags, while the Sport conserves roof width. |
| Exterior width | 24.7 in | 36 in | A second rack-mounted accessory needs a real width plan. |
| Empty weight | 34 lb | 53 lb on current product page | The Yakima uses 19 lb more of a shared roof-load budget. |
| Exterior length | 75.2 in | 84 in | Check front overhang, hatch movement and where the unloaded box will be stored. |
| Opening access | Dual-sided | Dual-sided | Either can be loaded from the side that remains accessible. |
What you give up
Every choice has a cost
If you choose Thule Force 3 L Sport
- The 11 cu ft interior is modest for family luggage.
If you choose Yakima SkyBox NX XL
- Its 53 lb empty weight leaves less payload for bikes and cargo.
Recommendation switch
The decision flips if...
I need 190 cm skis inside the box
Choose Yakima SkyBox NX XL. The NX 18 covers that length and the Sport does not.
My approved rack must also carry a bike and my skis are short
Choose Thule Force 3 L Sport. Its narrower and lighter shell leaves more room in both budgets.
What matters in practice
How to make the call
Decide whether the roof carries one thing or two
The Sport is attractive when a bike and box must share the rack. Its width advantage is meaningful, but the bicycle and its carrier can consume the roof payload quickly. Verify clamp positions, lid travel and vehicle fit with the full mixed-accessory layout.
Use the wide box when its space solves a real load
The NX 18 is a straightforward choice for longer skis and bulky family luggage when the box has the roof to itself. It adds seven cubic feet over the Sport. That space should be filled with appropriately light cargo after the rack and 53 lb box have been deducted.
Keep access and storage in the decision
Both open from either side, so access is not a reason to favor one automatically. The larger Yakima is also 8.8 inches longer outside. Check the hatch with Yakima’s measurement method and plan where that 84-inch shell will live between trips.
What this comparison cannot tell you
- These are manufacturer fit limits and planning examples, not a vehicle-specific installation approval.
- Yakima documents differ by about 1 lb on empty weight. Use the heavier published figure until the supplied box is confirmed. No wind-noise or fuel-economy winner is established.
What the facts say
What the comparison shows
Useful conclusions from the current roof cargo boxes comparison, followed by the checked facts used to reach them.
See the checked facts and calculation notes
| Product | Needs matched | Checked facts | Source records |
|---|---|---|---|
| Thule Force 3 L Sport |
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| Yakima SkyBox NX XL |
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Ready to choose?
Check the price. Read the owner reviews.
Open either model on Amazon to check the current price, customer reviews and delivery options.
Thule Force 3 L Sport
Your skis fit within 175 cm and you need a narrow shell.
See price & reviews on AmazonYakima SkyBox NX XL
You need skis up to 195 cm.
See price & reviews on AmazonLinks open in a new tab.